I understand why someone might buy from an established reseller, if they are confident the bag is authentic. The reseller might have the exact bag they are looking for, and the price, while high, may be worth paying for them. Not everyone can get exactly what they want when they want it from an Hermes boutique. Even if the bag eventually materializes, if it takes a long time prices go up so much that it might not be that much more than what a reseller charged previously.
But craigslist is different from established resellers, obviously.